The present invention relates to liquid crystal displays and more particularly to luminaires for backlighting liquid crystal display matrixes.
Projection type liquid crystal displays require proper backlighting to assure good performance. The intensity of illumination should be substantially uniform across the display matrix and the light provided should preferably be at least partially collimated. Furthermore, in many applications such as for aircraft instrumentation the luminaire must be as compact as possible since the available space is very limited and should preferrably have a thin planar shape for convenient attachment to the back of the display matrix.
In the past luminaires for use in backlighting liquid crystal display matrixes have ordinarily been constructed of fluorescent tubes aligned edge to edge to form a solid bank of lighting devices. In this way all of the light from the front surfaces of the tubes is used in providing light of relatively uniform intensity across the entire bank. However, this arrangement is not efficient since very little light is used from the backsides of the tubes. Parabolic type reflectors have been employed in some luminaire designs for reflecting light from the rear surfaces of fluorescent tubes used as lighting sources. Unfortunately, this style of reflector is not well suited to use with fluorescent tubes which are not like line sources and consequently very little gain in efficiency is actually obtained through the use of such reflectors.
It is therefore an object of the present invention to provide a luminaire for use in backlighting projection type liquid crystal display matrixes having improved efficiency which provides light of relatively uniform intensity across the back of the display matrix.
It is another object of the present invention to provide a luminaire for use in backlighting liquid crystal display matrixes which is compact in design having a thin and planar shape well adapted for attachment to the back of a liquid crystal display matrix.
It is a further object of the present invention to provide a luminaire for use in backlighting liquid crystal display matrixes which provides at least partially collimated light to the display matrixes and efficiently makes use of the light emitted from the backsides of fluorescent tubes used as lighting sources.